The F1-ATPase of Escherichia coli has been dissociated into its 5 subunits and completely reconstituted. We are studying the binding of substrates and inhibitors to each of the native subunits. We plan to modify the alpha subunit with affinity labels which are structural analogues of ATP and examine effect of such modifications on reconstitution of the ATPase complex. We shall search for other, not yet described, subunits of ECF1. We have isolated a complex of the gamma and epsilon subunit. We plan to isolate other such complexes containing part of the F1-ATPase and study their properties. Other methods for isolating F1-ATPase mutants will be explored. We found that external ATP causes a huge increase in passive permeability of transformed, but not untransformed, mouse fibroblasts. The process is reversible. The mechanism appears to involve the phosphorylation and dephosphorylation of a membrane protein of molecular weight 45,000, which we have solubilized. We plan to purify this protein. We plan to solubilize and purify the membrane bound kinase which carries out the phosphorylation. Finally, we wish to find out if this membrane bound protein kinase is itself subject to phosphorylation and dephosphorylation.